Selective Eating of the Acyanogenic Form of the Plant Lotus corniculatus L. by Various Animals

Abstract

WILD populations of the tetraploid plant Lotus corniculatus L. (birds' foot trefoil) are polymorphic for the presence or absence of a cyanogenic glucoside. This character is genetically controlled¹, the gene responsible for producing the glucoside being dominant over its allelomorph. Hydrocyanic acid is evolved on hydrolysis of the glucoside when the stems or leaves are injured. Corkill² has shown that with Trifolium repens L. the change in the colour of sodium picrate paper from yellow to brick red is proportional to the amount of hydrocyanic acid produced and hence to the glucoside content of the plant. The plants are scored from 0 (no glucoside) to 6 by matching the colour-change in the picrate paper against a series of standards.